The transforming region of the DNA tumor viruses. SV40 and JCV, and adenovirus regulates transcription of viral and cellular genes. The purpose of these studies is to investigate the mechanism by which the T/t antigen(s) and E1A proteins modulate transcription and its relationship to cellular transformation. In adenovirus, The EIIA upstream sequences which contain the binding sites for proteins ATF and EIIF act as an enhancer and can be trans-activated by both EIA and SV40 T/t antigens. Specific mutation of either the ATF and EIIF binding sites inhibited the EIIA enhancer 200-fold. Analysis of insertion mutation suggests that the spatial alignment of the upstream ATF and EIIF binding sites with respect to the downstream EIIF binding site on the DNA helix is important. Consistent with previous findings, using gel shift analysis we demonstrate that the binding activity of EIIF is increased following wild-type adenovirus infection. In contrast, using identical gel shift conditions, the binding activity of ATF is decreased by viral infection . Since ATF is actually a family of closely related transcription factors, studies are in progress to look at differential regulation in response to adenovirus infection.